package com.util;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public final class AESUtilFinal {
	

	// AES密码器
	private static Cipher cipher;

	// 字符串编码
	private static final String KEY_CHARSET = "UTF-8";

	// 算法方式
	private static final String KEY_ALGORITHM = "AES";

	// 算法/模式/填充
	private static final String CIPHER_ALGORITHM_CBC = "AES/CBC/PKCS5Padding";

	// 私钥大小128/192/256(bits)位 即：16/24/32bytes，暂时使用128，如果扩大需要更换java/jre里面的jar包
	private static final Integer PRIVATE_KEY_SIZE_BIT = 128;
	private static final Integer PRIVATE_KEY_SIZE_BYTE = 16;


	public static void main(String[] args) {
		String secretKey = "1234567812345678";
		String text = "test123测试";
		String miwen = encrypt(secretKey, text);
		System.out.println("密文为：" + miwen);
		String mingwen = decrypt(secretKey, miwen);
		System.out.println("明文为：" + mingwen);
	}
	
	/**
	 * 加密
	 * 
	 * @param secretKey
	 *            密钥：加密的规则 16位
	 * @param plainText
	 *            明文：要加密的内容
	 * @return cipherText
	 * 			     密文：加密后的内容，如有异常返回空串：""
	 */
	public static String encrypt(String secretKey, String plainText) {
		if (secretKey.length() != PRIVATE_KEY_SIZE_BYTE) {
			throw new RuntimeException("AESUtil:Invalid AES secretKey length (must be 16 bytes)");
		}
		
		// 密文字符串
		String cipherText = "";
		try {
			// 加密模式初始化参数
			initParam(secretKey, Cipher.ENCRYPT_MODE);
			// 获取加密内容的字节数组
			byte[] bytePlainText = plainText.getBytes(KEY_CHARSET);
			// 执行加密
			byte[] byteCipherText = cipher.doFinal(bytePlainText);
			cipherText = new String (Base64.encodeBase64(byteCipherText));
			
		} catch (Exception e) {
			throw new RuntimeException("AESUtil:encrypt fail!", e);
		}
		return cipherText;
	}

	/**
	 * 解密
	 * 
	 * @param secretKey
	 *            密钥：加密的规则 16位
	 * @param cipherText
	 *            密文：加密后的内容，即需要解密的内容
	 * @return plainText 
	 * 		  	      明文：解密后的内容即加密前的内容，如有异常返回空串：""
	 */
	public static String decrypt(String secretKey, String cipherText) {
		if (secretKey.length() != PRIVATE_KEY_SIZE_BYTE) {
			throw new RuntimeException("AESUtil:Invalid AES secretKey length (must be 16 bytes)");
		}
		
		// 明文字符串
		String plainText = "";
		try {
			initParam(secretKey, Cipher.DECRYPT_MODE);
			
			byte[] byteCipherText = Base64.decodeBase64(cipherText.getBytes());
			// 解密
			byte[] bytePlainText = cipher.doFinal(byteCipherText);
			plainText = new String(bytePlainText, KEY_CHARSET);
		} catch (Exception e) {
			throw new RuntimeException("AESUtil:decrypt fail!", e);
		}
		return plainText;
	}
	
	/**
	 * 初始化参数
	 * @param secretKey
	 * 			 	密钥：加密的规则 16位
	 * @param mode
	 * 				加密模式：加密or解密
	 */
	public static void initParam(String secretKey, int mode) {
		try {
			// 防止Linux下生成随机key
			SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
	        secureRandom.setSeed(secretKey.getBytes());
			// 获取key生成器
			KeyGenerator keygen = KeyGenerator.getInstance(KEY_ALGORITHM);
			keygen.init(PRIVATE_KEY_SIZE_BIT, secureRandom);
			
			// 获得原始对称密钥的字节数组
			byte[] raw = secretKey.getBytes();
			
			// 根据字节数组生成AES内部密钥
			SecretKeySpec key = new SecretKeySpec(raw, KEY_ALGORITHM);
			// 根据指定算法"AES/CBC/PKCS5Padding"实例化密码器
			cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC);
			IvParameterSpec iv = new IvParameterSpec(secretKey.getBytes());
			System.out.println("iv:" + new String(iv.getIV()));
			cipher.init(mode, key, iv);
		} catch (Exception e) {
			throw new RuntimeException("AESUtil:initParam fail!", e);
		}
	}
	

}
